Aubin Archambault, PhD Thesis, Université de Lyon (2023)
The usual laws of thermodynamics are robust and can be applied to large range of macroscopic systems. However, when thermal fluctuations are on the same scale as the studied phenomena, these laws only describe the average behaviour. While it is impossible to macroscopicaly extract work from thermal fluctuations, this limit can be overcome by adapting the protocols based on the outcome of a measurement. This thesis presents an experimental realisation of information engine, monothermal cycles whose evolution is determined by the result of a measurement on the system. We show that it is then possible to extract energy from thermal fluctuations, and optimise the engine to maximise the work extraction in different regimes. These measurements are used to test recent theoretical works and explore the underdamped regime, usually harder to study. They also highlight specific effects of this underdamped regime. Two supplementary works are presented. The first presents two model for the description of the flexural modes of micro-cantilevers loaded with massive spheres. These models are completed by experiments, made possible by the development of microfabrication process. The second presents the development of force measurement device, adapted to forces in the range of the piconewton. This device is used to measure Casimir forces, up to a distance of 30nm.